This application is based upon, claims the benefit of priority of, and incorporates by reference, the contents of Japanese Patent Applications No. 2001-232749 filed Jul. 31, 2001 and No. 2002-124745 filed Apr. 25, 2002.
1. Field of the Invention
The present invention relates to a turbine fuel pump for pressure-feeding fuel from a fuel tank to a fuel injection apparatus on a vehicle.
2. Description of the Related Art
A turbine fuel pump may be used for pressure-feeding fuel in a fuel tank to a fuel injection apparatus on a vehicle such as an automobile. The turbine fuel pump (also referred to as a xe2x80x9cWestco pumpxe2x80x9d) generally includes a disk-shaped impeller having multiple blades and blade grooves alternately formed along the circumference on an outer peripheral surface of the impeller, a motor housing that has C-shaped pump flow passages communicating to the blade grooves and that also stores the rotating impeller, and a motor for driving the impeller.
There have been needs for increasing the efficiency of a fuel supply apparatus including a fuel pump in view of decreasing fuel consumption of vehicles and atomizing fuel for low emissions. For these purposes, the shape of the blades and the blade grooves of the impeller, and the shape of a fuel outlet opening to which a terminal end of a pump flow passage of the motor housing communicates, have been improved.
However, a smooth flow of fuel at a fuel inlet opening, with which a start end of the pump passage of the motor housing communicates, has not been sufficiently studied. For example, in a turbine fuel pump in FIG. 12 and FIG. 13 (see Japanese Patent Laid-Open Publication No. Hei. 11-117890), a motor housing 120 is attached to a pump housing 135, and comprises a pump cover 122 on one side (a bottom side) 131 of the impeller 130, and a pump casing 126 on the other side (a top side) 132 of the impeller 130.
The pump cover 122 and the pump casing 126 form a circular impeller storage space, and a C-shaped pump flow passage 125. A fuel inlet opening 123 is formed on the pump cover 122 for communicating to a start end 125a. A fuel outlet opening 127 is formed on the pump casing 126 for communicating to a terminal end 125b of the pump flow passage 125. The impeller 130 has multiple blades 133 and blade grooves 134 alternately formed on an outer periphery, and is stored in the impeller storage space. The blade grooves 134 communicate to the pump flow passage 125.
The fuel inlet opening 123 passes through the pump cover 122 in the axial direction (in the vertical direction in FIG. 12). Thus, the flow direction of the fuel drawn from the fuel inlet opening 123 into the start end 125a is orthogonal to the rotational direction of the impeller 130, and is orthogonal to the flow direction of the fuel in the pump flow passage 125. The direction of the fuel flow changes by almost a right angle at the start end 125a. 
As a result, the flow rate of the fuel decreases at the start end 125a, and a loss of pressure (a pressure loss) is generated in the fuel. Consequently, a local negative pressure is generated in the fuel pressure at the start end 125a, a part of the fuel is vaporized, and the flow quantity decreases accordingly in the pump flow passage 125. Especially when the temperature of the fuel is high, the local negative pressure increases the effect of vaporizing the fuel, and the flow quantity of the fuel markedly decreases.
Then, the flow quantity of the pressure-fed fuel from the start end 125a to the terminal end 125b decreases, and the outlet quantity from the fuel outlet opening 127 decreases. Thus, problems such as the pump efficiency scarcely increases, and the pump performance decreases when the fuel temperature is high.
The present invention was devised in view of the above problems, and an object is to provide a turbine fuel pump for preventing a pressure loss at the start end of the pump flow passage and for preventing the accompanying resultant local negative pressure. Additionally, increasing pump efficiency and overall operating performance while at a high temperature is a goal.
The present inventor studied a constitution of a first housing where a direction of drawing the fuel at the start end of the side groove on the inlet side is not orthogonal to the rotational direction of the impeller, and is not orthogonal to the fuel flow direction in the side groove on the inlet side. As a result, such an idea as the fuel inlet opening not being made as a port (an opening) but as a fuel inlet passage having a predetermined length was devised resulting in completion of the present invention.
A turbine fuel pump of a first aspect of the present invention includes a disk-shaped impeller provided with multiple blades and multiple blade grooves formed alternately around a circumference on a first surface and on an outer periphery of the second surface, and a pump housing for storing the impeller during rotation.
The pump housing includes a disk-like first housing provided on a first side of the impeller, and a disk-like second housing provided on a second side of the impeller. The first housing includes a side groove on an inlet side, and a fuel inlet passage. The side groove on the inlet side is formed on an inner side surface of the first housing, and extends from a start end to a terminal end in approximately a C-shape.
The fuel inlet passage extends from the start end of the side groove on the inlet side toward the inside in the radial direction, and simultaneously toward the terminal end, and has an opening on an outer side surface of the first housing. The second housing includes a side groove on an outlet side, and a fuel outlet opening. The side groove on an outlet side is formed on an inner side surface of the second housing, and extends from a start end to a terminal end in approximately a C-shape. The fuel outlet opening communicates to the terminal end of the side groove on the outlet side. The impeller rotates to increase the pressure of fuel while the fuel drawn from the fuel inlet passage is being transported to the fuel outlet opening.
In this fuel pump, the fuel inlet passage extends from the start end toward the terminal end of the side groove on the inlet side, and has the opening on the outer side surface. Thus, the fuel flowing from the fuel inlet passage to the start end is not orthogonal to the fuel flow in the side groove on the inlet side, and is not orthogonal to the rotational direction of the impeller. As a result, the decrease of the flow rate when the inlet fuel merges is small, the loss of the pressure is prevented at the start end, and the inlet fuel smoothly merges with the fuel in the side groove on the inlet side. Additionally, since a centrifugal force is applied to the fuel in the fuel inlet passage, the fuel flow rate increases.
A turbine fuel pump of an eleventh aspect of the present invention includes a disk-shaped impeller provided with multiple blades and multiple blade grooves formed alternately in the circumferential direction on a first surface and on a second surface around an outer periphery. Additionally, a pump housing is provided for storing said rotating impeller. The pump housing includes a disk-like first housing provided on one side of the impeller, and a disk-like second housing provided on the other side of the impeller.
The first housing includes a side groove on an inlet side, and a fuel inlet passage. The side groove on the inlet side is formed on an inner side surface of the first housing, and extends from a start end to a terminal end in approximately a C-shape. The fuel inlet passage extends from the start end of the side groove on the inlet side to an opening on an outer side surface of the first housing. The opening is positioned on the inside of the start end in the radial direction, and simultaneously on a side close to the terminal end in the circumferential direction.
The second housing includes a side groove on an outlet side in approximately a C-shape formed on an inner side surface thereof, and a fuel outlet opening communicating to a terminal end of the side groove on the outlet side. The impeller rotates to increase a fuel pressure while the fuel drawn from the fuel inlet passage is being transported to the fuel outlet opening.
In this fuel pump, the opening on the outer side surface of the first housing is placed on the inside of the start end in the radial direction, and on a side close to the terminal end in the circumferential direction. Thus, the fuel flowing from the fuel inlet passage to the start end is not orthogonal to the fuel flow in the side groove on the inlet side and the rotational direction of the impeller. As a result, the decrease of the flow rate when the inlet fuel merges is small, the loss of the pressure is prevented at the start end, and the inlet fuel smoothly merges with the fuel in the side groove on the inlet side. Additionally, because a centrifugal force is applied to the fuel in the fuel inlet passage, its flow rate increases.
In turbine fuel pumps of second and twelfth aspects, the fuel inlet passage extends linearly in the turbine fuel pumps as in the first and eleventh aspects. With these fuel pumps, the fuel flows smoothly in the fuel inlet passage.
In turbine fuel pumps of third and thirteenth aspects, the fuel inlet passage is tilted or angled with respect to a tangent of the start end in a plan view of the inner side surface of the first housing in the turbine fuel pumps of the second and twelfth aspects. With these fuel pumps, the fuel inlet direction is not orthogonal to the fuel flow in the side groove on the inlet side. Thus, the flow rate does not sharply decrease at the start end, and the loss of pressure is prevented.
In turbine fuel pumps of the fourth and fourteenth aspects, the fuel inlet passage is tilted with respect to a bottom surface of the side groove on the inlet side in a section in the axial direction of the turbine fuel pump as in the turbine fuel pumps of the second and twelfth aspects. With these fuel pumps, the inlet direction of the fuel is not orthogonal to the rotational direction of the impeller. Thus the flow rate does not sharply decrease at the start end, and the fuel smoothly flows into the blade grooves.
In turbine fuel pumps of the fifth and fifteenth aspects, the length of the inlet passage is twice to four times the thickness of the first housing in the turbine fuel pumps of the first and eleventh aspects. With these fuel pumps, since the fuel inlet passage is not too long, the pressure loss is small while the fuel is flowing through the fuel inlet passage.
In a turbine fuel pump of a sixth aspect, the fuel inlet passage includes a tilted groove that is tilted with respect to the bottom surface of the side groove on the inlet side, which gradually increases its depth, and a through hole tilted with respect to the tilted groove, and having an opening on the outer side surface of the first housing in the turbine fuel pump of the fourth aspect. With this fuel pump, the fuel smoothly flows through the fuel inlet passage.
In a turbine fuel pump of a seventh aspect, a boundary between the fuel inlet passage and the side groove on the inlet side is rounded as in the turbine fuel pumps of the fourth aspect. With this fuel pump, the fuel flows even more smoothly through the fuel inlet passage.
In a turbine fuel pump of an eighth aspect, the side groove on the inlet side includes an inner side groove and an outer side groove concentrically formed as in the turbine fuel pump of the first aspect. A start end of the inner side groove and a start end of the outer side groove are formed in the fuel inlet passage. With this fuel pump, the flow quantity of the pressure-fed fuel is doubled to increase the pump efficiency, and simultaneously, the one fuel inlet passage is shared by the two side grooves on the inlet side.
In a turbine fuel pump of a ninth aspect, the impeller includes multiple communication holes passing from one surface to another surface inside the multiple blades and the multiple blade grooves in the radial direction on one surface and on the other surface as in the turbine fuel pump of the first aspect. With this fuel pump, since the fuel flows through the communication holes at the start end and the terminal end of the pump flow passage, it is not necessary to form communication parts in the first housing and the second housing.
In a turbine fuel pump of a tenth aspect, a first communication part is formed on the outer peripheral side of the start end of the side groove on the inlet side in the turbine fuel pump of the first aspect. A second communication part is formed on the outer peripheral side of the terminal end of the side groove on the inlet side. A third communication part is formed on the outer peripheral side of the start end of the side groove on the outlet side. A fourth communication part is formed on the outer peripheral side of the terminal end of the side groove on the outlet side. The first communication part communicates to the third communication part, and the second communication part communicates to the fourth communication part. With this fuel pump, since the fuel flows through the first to fourth communication parts of the pump housing on the start end and the terminal end of the pump flow passage, it is not necessary to form communication holes on the impeller.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.